I've tried a bunch of different stuff to make the physics movement behave similarly with different frame rates but it's pretty awkward
a lower frame rate means the resulting velocity from apply force/impulse is much bigger, so you jump higher for example
something I experimented with and ended up keeping was making instance variables on each physics object, 'forceX' and 'forceY' and instead of 'apply force..' i use 'add to forceX'/add to forceY instead. and at the very end of the events sheet, it sets the velocity X to it's current velocity X plus the forceX value.. and then sets the forceX variable back to 0 for the next tick. Same for ForceY
now I dont know for sure whats going on under the hood, but i guess this means it's not doing a bunch of force iterations each tick, just one. The effect this has is that a lower frame rate means you jump slightly lower instead of higher (the difference is lessened too). Which is arguably better.. just try your best to make the game run at a consistent 60 fps. and maybe let the player know that 60 fps is really how it should be played.